Re: [hurd, commited] socket: Fix tst-cmsghdr-skeleton.c use of cmsg_len

[Samuel Thibault]

Andreas Schwab, le lun. 01 mai 2023 16:03:32 +0200, a ecrit:
> On Mai 01 2023, Samuel Thibault wrote:
> 
> > Andreas Schwab, le lun. 01 mai 2023 15:38:45 +0200, a ecrit:
> >> On Mai 01 2023, Samuel Thibault wrote:
> >> 
> >> > cmsg_len is supposed to be socklen_t according to standards, but it was 
> >> > made
> >> > size_t on Linux, see BZ 16919. For ports that have it socklen_t, 
> >> > SIZE_MAX is
> >> > too large. We can however explicitly cast it to the type of cmsg_len so 
> >> > it
> >> > will fit according to that type.
> >> > ---
> >> >  socket/tst-cmsghdr-skeleton.c | 2 +-
> >> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >> >
> >> > diff --git a/socket/tst-cmsghdr-skeleton.c 
> >> > b/socket/tst-cmsghdr-skeleton.c
> >> > index 296a0a8581..9516139f87 100644
> >> > --- a/socket/tst-cmsghdr-skeleton.c
> >> > +++ b/socket/tst-cmsghdr-skeleton.c
> >> > @@ -49,7 +49,7 @@ RUN_TEST_FUNCNAME (CMSG_NXTHDR_IMPL) (void)
> >> >    /* The first header length is so big, using it would cause an 
> >> > overflow.  */
> >> >    cmsg = CMSG_FIRSTHDR (&m);
> >> >    TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf);
> >> > -  cmsg->cmsg_len = SIZE_MAX;
> >> > +  cmsg->cmsg_len = (__typeof (cmsg->cmsg_len)) SIZE_MAX;
> >> 
> >> What does that fix?
> >
> > 64bit hurd, where cmsg_len is socklen_t as the standards require (thus
> > 32bit).
> 
> And what does it fix?

You mean the error message? The SIZE_MAX constant truncation down from
64bit to 32bit:

x86_64-glibc-gnu-gcc tst-cmsghdr.c -c -std=gnu11 -fgnu89-inline  -g -O2 -Wall 
-Wwrite-strings -Wundef -Werror -fmerge-all-constants -frounding-math 
-fno-stack-protector -fno-common -Wno-parentheses -Wstrict-prototypes 
-Wold-style-definition -fmath-errno    -fPIE         -I../include 
-I/mnt/scratch/sthibault/build-glibc/build/glibcs/x86_64-gnu/glibc/socket  
-I/mnt/scratch/sthibault/build-glibc/build/glibcs/x86_64-gnu/glibc  
-I../sysdeps/mach/hurd/x86_64  -I../sysdeps/mach/hurd/x86  
-I../sysdeps/mach/hurd/x86_64/htl  -I../sysdeps/mach/hurd/htl  
-I../sysdeps/hurd/htl  -I../sysdeps/mach/htl  -I../sysdeps/htl/include 
-I../sysdeps/htl  -I../sysdeps/pthread  -I../sysdeps/mach/hurd/x86/htl  
-I../sysdeps/x86_64/htl  -I../sysdeps/x86/htl  -I../sysdeps/mach/hurd  
-I../sysdeps/gnu  -I../sysdeps/unix/bsd  -I../sysdeps/unix/inet  
-I../sysdeps/mach/x86_64  -I../sysdeps/mach/x86  -I../sysdeps/mach/include 
-I../sysdeps/mach  -I../sysdeps/x86_64/64  -I../sysdeps/x86_64/fpu/multiarch  
-I../sysdeps/x86_64/fpu  -I../sysdeps/x86/fpu  -I../sysdeps/x86_64/multiarch  
-I../sysdeps/x86_64  -I../sysdeps/x86/include -I../sysdeps/x86  
-I../sysdeps/ieee754/float128  -I../sysdeps/ieee754/ldbl-96/include 
-I../sysdeps/ieee754/ldbl-96  -I../sysdeps/ieee754/dbl-64  
-I../sysdeps/ieee754/flt-32  -I../sysdeps/hurd/include -I../sysdeps/hurd  
-I../sysdeps/unix  -I../sysdeps/posix  -I../sysdeps/wordsize-64  
-I../sysdeps/ieee754  -I../sysdeps/generic -I../hurd 
-I/mnt/scratch/sthibault/build-glibc/build/glibcs/x86_64-gnu/glibc/hurd/ 
-I../mach 
-I/mnt/scratch/sthibault/build-glibc/build/glibcs/x86_64-gnu/glibc/mach/ -I.. 
-I../libio -I.  -D_LIBC_REENTRANT -include 
/mnt/scratch/sthibault/build-glibc/build/glibcs/x86_64-gnu/glibc/libc-modules.h 
-DMODULE_NAME=testsuite -include ../include/libc-symbols.h  -DPIC     
-DTOP_NAMESPACE=glibc -o 
/mnt/scratch/sthibault/build-glibc/build/glibcs/x86_64-gnu/glibc/socket/tst-cmsghdr.o
 -MD -MP -MF 
/mnt/scratch/sthibault/build-glibc/build/glibcs/x86_64-gnu/glibc/socket/tst-cmsghdr.o.dt
 -MT 
/mnt/scratch/sthibault/build-glibc/build/glibcs/x86_64-gnu/glibc/socket/tst-cmsghdr.o
In file included from ../include/stdint.h:1,
                 from tst-cmsghdr-skeleton.c:24,
                 from tst-cmsghdr.c:31:
tst-cmsghdr-skeleton.c: In function 'run_test_CMSG_NXTHDR':
../stdlib/stdint.h:227:33: error: conversion from 'long unsigned int' to 
'socklen_t' {aka 'unsigned int'} changes value from '18446744073709551615' to 
'4294967295' [-Werror=overflow]
  227 | #  define SIZE_MAX              (18446744073709551615UL)
      |                                 ^
tst-cmsghdr-skeleton.c:52:20: note: in expansion of macro 'SIZE_MAX'
   52 |   cmsg->cmsg_len = SIZE_MAX;
      |                    ^~~~~~~~

Samuel